[RMNB]

Picked up 2016 M235i. It appears they have a square set...225/40/18. My question is who out there has put on 255/35/18's on the rear with a stock suspension? I'm not sure if the rear wheel is 7.5 or 8" wide.

Need some direction before I order Pilot 4s tires.

Thanks in advance!

[ralawren]

Normally the square set up has 7.5" wheels on all four corners. The wheel size is stamped on the back side of the wheel.

[msej449]

Here in the UK the following square setup is the default certified by BMW for winters for my stock 2016 M235i:

▪ 7.5Jx17 + 225/45 R17 94V XL

Whereas the ex-factory summer staggered setup is

▪ Front: 7.5Jx18 + 225/40 R18 92Y
▪ Rear: 8.0Jx18 + 245/35 R18 92Y

As implied by @ralawren you need to check what you've actually got fitted first. Then it'll be clearer what options you have if you want wider rear tyres. The UK 19" setup certified by BMW is

▪ Front: 7.5Jx19 + 225/35 R19 88Y (offset 45)
▪ Rear: 8.0Jx19 + 245/30 R19 89Y (offset 52)

which isn't to say that you can't fit other combinations, but in my experience, you need to understand what you're getting and giving up if you go outside the certified config's. For me, wheel/tyre options are a bit of a zero sum game: you can't have your cake and eat it (e.g. wider tyres in the dry may improve stability/grip under acceleration, but at the cost of reduced resistance to aquaplaning when cornering in heavy rain, etc.). And BTW, I've no issue with people wanting to change wheels/tyres for purely aesthetic reasons (your car, you do what you want), just there's usually a corresponding handling change that comes with it.

[Addendum: @335xi is the M235i shod for winter, then? If so, you might consider a separate set of summer wheels and tyres is better than trying to 'squeeze' big summer tyres onto narrow winter wheels.]

[dradernh]

Originally Posted by 335xi Beast

255/35/18...Pilot 4s

FWIW, the rim width range for that tire is 8.5" - 10", and the measured rim width is 9.0".

The Rack explains these terms better than I can:

Rim Width Range: https://www.tirerack.com/tires/tiret...jsp?techid=198.

Measured Rim Width: https://www.tirerack.com/tires/tiret...jsp?techid=199.

[VMRWheels]

Originally Posted by dradernh

FWIW, the rim width range for that tire is 8.5" - 10", and the measured rim width is 9.0".

The Rack explains these terms better than I can:

Rim Width Range: https://www.tirerack.com/tires/tiret...jsp?techid=198.

Measured Rim Width: https://www.tirerack.com/tires/tiret...jsp?techid=199.

This.

Whether it's 7.5" or 8" wide, technically, the 255/35/18 is too wide for that wheel per manufacture recommendation. If your car has a 225/40/18 square setup, it's probably a 7.5" wheel. Maybe consider bumping up the front and rear to a 235/40/18 instead. That will allow you to rotate your tires as needed.

[RMNB]

Originally Posted by VMRWheels

This.

Whether it's 7.5" or 8" wide, technically, the 255/35/18 is too wide for that wheel per manufacture recommendation. If your car has a 225/40/18 square setup, it's probably a 7.5" wheel. Maybe consider bumping up the front and rear to a 235/40/18 instead. That will allow you to rotate your tires as needed.

I did confirm today both are 7.5" front and rear. With that said I suppose I will stick with a square set up based upon the rotation aspect BUT THEY STILL LOOK SKINNY AND WIMPY.

Next question...do I automatically need an alignment afterward if I stay square but bump to 235/40/18?? 19's would look better but not wanting to blow money BUT I do have the 20's Vorsteiner VFF-107's from my 550i... 235/35/20 and 285/30/20. Wishful thinking... no chance. That's why I'm selling them.

[aerobod]

Originally Posted by 335xi Beast

Next question...do I automatically need an alignment afterward if I stay square but bump to 235/40/18??

No alignment needed, but the specified wheel width for 235/40/18 tyres is 8.0" to 9.5". 225/40-18 tyres are the widest for a 7.5" wheel to stay within manufacturers' specifications.

[ralawren]

Originally Posted by aerobod

No alignment needed, but the specified wheel width for 235/40/18 tyres is 8.0" to 9.5". 225/40-18 tyres are the widest for a 7.5" wheel to stay within manufacturers' specifications.

So, you have to decide how much risk you want to take based on your driving style. I actually drove around for a month with 245/35/18 tires on my 7.5" front wheels by mistake. BMW installed 4 rear tires on my car and I didn't notice for a week. Once I did the mechanic at the dealer said it would be safe.

Of course I checked with Michelin and TireRack and they both said absolutely not. I auto-x occasionally and was concerned that I would break the bead under spirited driving. I had the dealer replace the tires with 225s and purchased the 245s for $100 each.

So the 245 fits on the front without rubbing on the 7.5" wheel but it is not recommended.

[RMNB]

Originally Posted by VMRWheels

This.

Whether it's 7.5" or 8" wide, technically, the 255/35/18 is too wide for that wheel per manufacture recommendation. If your car has a 225/40/18 square setup, it's probably a 7.5" wheel. Maybe consider bumping up the front and rear to a 235/40/18 instead. That will allow you to rotate your tires as needed.

I just ordered 235/40/18's Mich PS4s all around.
Am I good to go? Any fitment issues??

[ralawren]

Originally Posted by 335xi Beast

I just ordered 235/40/18's Mich PS4s all around.
Am I good to go? Any fitment issues??

No fitment issue but a 235 on a 7.5" wheel is too large if you drive aggressively. Call Michelin Customer service or TireRack for advice.